Purfication of sugar solutions by means of spongy ion exchangers



United States Patent Ofitice 3,122,455 Patented Feb. 25, 1964PURIFECATION OF SUGAR SGLUI'IGNS BY MEANS F SPQNGY 0N EXCHANGERS ErhardMeier, deceased, late of Leveriiusen, Germany, by Ingeborg I Meier,Jurgen-Dietrich Meier, and igrid Meier, heirs, Leverlrusen, Germany, andherbert erte, Lever-kneel Germany, assignors to Farheniahriken BayerAhnengesehschatt, Lever-liaison, Germany, a corporation of Germany IfDrawing. Fiied Feb. 3, 196b, fier. N 7,483 Ciaims priority, appiicationGermany Feb. 16, 1959 15 iaims. (1. 127-46) The present inventionrelates to purification of sugar solutions by means of spongy ionexchangers and more especially by means of spongy cation exchangers.

It is known to remove salt from sugar solutions by means of ionexchangers. A procedure which is frequently used industrially is firstof all to extract the cations with a cation exchanger and to remove theacids liberated by a subsequenttreatment with an anion exchanger. Inorder to counteract the danger of formatron of invert sugar, it ishowever known to Work with the converse direction, is. using first ofall the anion exchanger and then the cation exchanger. In all cases,sugar solutions are obtained which in practice no longer contain anysalt-forming constituents.

When using these processes, it has also simultaneously been observedthat a more or less strong clarifying or decolorising is achieved. Thisdecolorising efiect is primarily produced by the anion exchanger. Anadditional observation was that these decolorising efiects subsided incourse of time or could only be maintained with difficulty by specialregenerating processes. As a consequence of these observations, specialadsorbents were then developed for quite special decolorising processes.However, even then the maintenance of the decolorising action involvesspecial and also costly regeneranng processes. This separatedecolorising and desaltmg can for economic reasons only be: used inexceptional cases.

Anion exchangers and especially strongly basic anion exchangers havealready been described, which are obta ned from cross-linked copolymersof an aromatic monovinyl compound and a coploymerizable cross-linkingagent, such as divinyl benzene, by haloalleylating the copolymer andaminating the haloalkylated copolymer with an amine, such astrimethyiamine or dimethylamino ethanol. Anion exchangers of this typeare for instance disclosed in United States patentspecifications-2,591,- 573, 2,591,574, 2,614,099, 2,616,877, 2,629,710,. 2,631,- 999,2,632,000, 2,642,417, 2,725,361, and 2,794,785.

The porosity of these resins is inversely proportional to' the degree ofcross-linkage of the copolymer matrix to which the ion-exchanging groupsare bonded. The anion exchangers being derived froma weakly crosslinlcedmatrix are capable of absorbing to a certain degree color bodies fromsugar solutions, but they have the drawback that they display a thighdegree of sWellability. Moreover, these resins are of homogeneousstructure, 'tl'llis is to say in swollen condition they are transparentas g ass.

Contrary thereto, the present invention deals with the purification ofsugar solutions by means of spongy synthetic ion exchangers.

These ion exchangers arepermeated by small cavities or veins andtherefore are apaque in swollen condition. Due to their large internalsurface these resins are capable to absorb large molecules, even if thematrix of said resins is comparatively highly cross-linked. They may beobtained in the form of hard solid products, distinguished by acomparatively small degree of swell'ability, so that the volume of theresin when soaked in water does not surpass about 2 to 5 times that ofthe original dry volume. 7

These spongy ion exchangers are also different in characteristics fromthe ion exchangers, the matrix of which is formed by a proliferous orpopcorn polymer. These products have a very high degree of swellability,for instance sulfonic acid exchangers of this type expand to at leasttwenty times their dry volume when soaked in water.

Under the term spongy ion exchanger, as used in the presentspecification, we understand non-proliferous synthetic water-insolubleion exchange resins, the matrix of which is formed of a cross-linkedorganic copolymer' of ieterogeneous' structure, such spongy ionexchangers be- ':ig disclosed in French patent specifications 1,199,562,1,205,505, and 1,211,485.

It has now been found that the decolorising effect in the purificationof sugar solutions by means of ion exchangers can be substantiallyimproved by using for this purification spongy cation exchangers.

This discovery is very surprising, since former observations indicatedthat the usual synthetic cation exchangers With a homogeneous gelstructure have in practice no decolorising effect, or only a very slightefl'ect. Clarification in juices which have travelled through suchcation exchangers is substantially determined by the change in pH valuewhich has occurred Furthermore, the opinion formerly held was that thecolor-yielding impurities in solutions containing sugar, more especiallyin beet or cane sugar juices, constitute substantially neutral or acidelements. Spongy cation exchangers are for example described in FrenchSpecification 1,205,505. These exchangers are able toabsorb relativelylarge molecules and to give the latter off again upon regeneration withconventional regeneration agents. By using these cation exchangers, itis therefore possible for the various color complexes contained in thesugar solutions to be absorbed by the ion exchangers which are specificfor them, whereby it is possible not only to increase the purity in thefinal product, but above all also to facilitate the necessaryregeneration. These cation exchangers can be used in ion exchangerplants for the purification of sugar solutions in the combination withanion exchangers as known per so. It is particularly suitable to usespongy anion exchangers. Such spongy anion exchangers are described byway of example in German specifications 1,045,102, 1,049,583 and 1,054,-715 or in French specifications 1,199,562, 1,217,732, and 1,211,485. Thesugar solutions may be first treated with the spongy cation exchanger inthe hydrogen form and then with the anion exchanger in the hydroxylform, Which exchangers may be arranged in suitable filter colurnnsthrough which the solutions are passed, but also the converse sequenceis possible. It is, however, also possible to choose combinations withmore than two filters connected in series. The choice of the mostsuitable combination is' determined by the character of the juice to bepurified. It is also possible for an anion =3 exchanger to be used inneutral exchange, preferably a quaternary anion exchanger with ahomogeneous gel or sponge structure and charged with chloride or sulfateions, which neutral exchanger is arranged for example before the said Hor OH exchangers, the said neutral quaternary exchanger actingexclusively as a decolorizing filter and not as a salt-extractingfilter. Furthermore, it is also possible to use the spongy cationexchangers and the anion exchangers simultaneously, as for instance in amixed-bed filter.

In the development of the present process, it has further been observedthat the color complexes absorbed by the spongy cation exchanger areabsorbed in a relatively narrow zone. This zone migrates through thefilter as the charging increases. The inorganic cations simultaneouslyabsorbed by the cation exchanger, such as for example Ca", Mg" and K,are responsible for this phenomenon, since they displace organicmolecules from the cation exchanger. This observation is at the sametime also evidence of the ease with which these color bodies may beremoved from the exchangers during regeneration.

As a result, there is provided yet another interesting possibility. If aconventional cation exchanger of homogeneous gel structure which cannotor can only slightly absorb color bodies or other large molecules isarranged before the spongy cation exchanger, the displacement effectwhich has been described is prevented. The first cation exchangerabsorbs practically only the strongly dissociated small ions, such asfor example Ca", Mg", K. The second following cation exchanger is thenoperated as a hydrogen ion exchanger and has only to take up thecolor-yielding complexes which are Weakly or not dissociated, a largeroutput being produced simultaneously by the avoidance of thedisplacement eifect.

For carrying through the processes disclosed in the following examplesthe following ion exchangers are used:

K Cation exchanger of homogeneous gel structure produced by sulfonatinga bead copolymer of 90 parts by weight of styrene and 10 parts by Weightof divinyl benzene.

K Spongy cation exchanger produced according to Exlample 3 of Frenchpatent specification 1,205,505 by sulfonating a copolymer of 90 parts byweight of styrene and 10 parts by weight of divinyl benzene, saidcopolymer being obtained by copolymerizing the cited monomers in aqueoussuspension in the presence of 100% by weight of white spirit, saidpercentage being calculated on the weight of the monomers.

K Spongy cation exchangers produced in the same manner as cationexchanger K with the variation that 80% of normal heptane are usedinstead of 100% of white spirit in the production of the styrene divinylbenzene copolymer.

K.;Carboxylic cation exchanger of homogeneous gel structure produced byalkaline saponification of a copolymer of 95 parts by weight of methylacrylate and 5 parts by weight of divinyl benzene, the cited copolymerbeing obtained by copolymerizing the aforementioned monomers in aqueoussuspension.

K -Spongy carboxylic cation exchanger produced according to theprescription given in Example 1 of French patent specification 1,205,505by saponifying a spongy copolymer of methyl acrylate and divinyl benzenewith the variation that only 5% by weight (as calculated on the amountof the monomers) of divinyl benzene and that 70% by weight (ascalculated on the weight of the monomers) of normal octane are usedinstead of decauol.

A Anion exchanger having tertiary amino groups and being of homogeneousgel structure produced according to the method applied for theproduction of anion exchanger A disclosed below with the variation thatno decanol is employed for the production of the copolymer matrix.

2 p ngy anion exchanger having tertiary amino groups produced accordingto Example 4 of French patent specification 1,199,562 by copolymerisingparts by weight of vinyl toluene and 10 parts by weight of ethyleneglycol dimethacrylate in aqueous suspension in the presence of 60% byweight (as calculated on the weight of the monomers) of normal decanol,chloromethylating the copolymer and aminating the chloromethylatedcopolymer by means of dimethyl amine. A Anion exchanger of homogeneousgel structure having tertiary amino groups produced according to-Example 7 of French patent specification 1,217,732 by aminomethylating apolystyrene which is cross-linked by means of 6% by weight of divinylbenzene and alkylating said aminomethylated cross-linked polystyrene bymeans of formaldehyde and formic acid. A Spongy anion exchanger havingtertiary amino groups obtained by producing a spongy copolymer of 90parts by weight of styrene and 10 parts by weight of divinyl benzeneaccording to the prescription given in Example i2 of French patentspecification 1,217,732, whereby the cited monomers are copolymerised inan aqueous sus pension in the presence of 70% (as calculated on theweight of monomers) of white spirit, aminomethylating said spongycopolymer according to the prescription given in the same example ofFrench patent specification 1,217,732 by reacting said copolymer with N-(chloromethyl)-phthalimide and hydrolising the reaction product obtainedand thereafter alkylating said aminomethylated copolymer according tothe prescription given in Example 9 of the cited French patentspecification by means of formaldehyde and formic acid.

Example 1 For removing the salt and color from a cane sugar solutionwith 25 Brix and a color index of 130 Stammer/ Brix there are used twoseries-connected filters, the first of which is filled with 1 litre of acation exchanger and the second with 1 litre of an anion exchanger. -Inthe first series, the cation exchanger K is used in the hydrogen formand the anion exchanger A is used in the hydroxyl form, both exchangershaving a homogeneous gel structure. In the second case, the cationexchanger K2 and the anion exchanger A are used, both having a spongestructure. The cation exchangers K and K are first regenerated with a10% aqueous hydro chloric acid solution and the anion exchangers A and Awith a 5% aqueous sodium hydroxide solution. Thereafter the exchangersare charged with the aforesaid cane sugar solution by passing 5 litresof solution through each filter within one hour, the degree ofdecolorizing being determined behind the cation exchanger and behind theanion exchanger after the passage of 1 litre in each case. Th; valueshereby obtained are set out in the following ta e:

Litres Decolorizing in percent after 1 2 3 4 5 V 6 7 29 29 28 27. 5 27.5 27 26. 5 32 32 32 31 31 31 31 69 69 68 67 65 63 55 After Ai 98 98 9898 98 98 97 From a comparison of the above data it becomes evident thatthe decolorizing etfect of the spongy exchangers is by far superior tothat obtained with the homogeneous exchangers. Example 2 tains theWeakly basic spongy anion exchanger A Filters l and 2 were regeneratedwith 10% aqueous hydrochloric acid solution and filter 3 with 5% aqueoussodium hydroxide solution. The specific loads used in chargarepercentages of removed color bodies determined after passage of thecited amounts of liquid through the respective exchangers.

ing the filters were the same as in Example 1. 5 Litres of filt t per mmThe following degrees of decolorizing in percent were ofExchanger 10 2030 40 50 60 70 80 90 100 found:

K1 13700000000 K1 75 70 65 63 60 5s 57 55 55 55 Litres of filtrate perlitre of exchanger 1 5 10 15 20 After met 1 32 20 2 2O 18 10 Similareffects are achieved when the spongy cation ex- After filter 2111:111172 e e0 60 so hanger 1s used for the purification of aqueous glucoseAfter filter 3 98 99 99 99 99 Solutions, as they are for instanceobtained by hydrolysis of starch or wood. After exhaustion, filters land 3 were regenerated and Example 5 used again for the purification ofthe sugar solution. 15 There were obtained the same values as indicatedabove. so'canfid Wood Solutlon, as 1t 13 obtalfled by The regenerationof filter 2 became necessary only after and hydrolYsls of Wood 18 finnedOver the cfamon ffilters 1 and 3 were regenerated six times. For therechanger K1 the hydr ogen fQYm, whre'by the morgamc generation offilter 2, the regenerant leaving filter 3 was caufms contiflmed SaldSolutlon are removed- The passed over filter 2 in order to remove thecolor bodies 20 Sultmg Sohmon f a Contented dry Substanc? of absorbed bythe cation exchanger contained in filter 2. Bnx and F Index of Stammer-P 3911mm! After mg washdwater leaving filter 3 was also passed over waspassed in parallel experiments over one litre each of filter 2, theregenerant leaving filter 2 became alkaline, the hm hanger's 1x K K Kand K whereby the whereby practically all color bodies were removed from25 g g g di Percent) for the decolonzmg were filter 2. After havingdischarged the alkaline regenerant by means of water, filter 2 wastransformed into the hydrogen form by means of 10% aqueous hydrochloricacid solution, whereby thelw-hole regenerant leaving said filter wasused for the preliminary regeneration of filter 1.

From the aforementioned data it becomes evident that the decolorizingachieved by the spongy cation exchanger K is considerably higher thanthat achieved by cation exchanger K having a homogeneous gel structure.

The aforementioned eliect is not only achieved with cane sugarsolutions, but also with beet sugar molasses and green juices.

Example 3 Litres of filtrate per litre of exchanger- 5 10 I I I Thenegative values in the above table indicate that the color of thefiltrate was higher than that of the infiuent solution. It is evidentthat with 20 litres of filtrate per litre of exchanger, K hasconsiderably higher decolorizing efiect than K The color bodies offilter K are discharged at an earlier sta e than those of K since filterK is exhausted by the cations absorbed from the sugar solution at anearlier stage as is the case with filter 14;.

In case that for carrying through the aforementioned experiment a beetsugar molasses is used, from which the inorganic cations are removed,the superior decolorizing action of the spongy cation exchanger becomesstill more evident, since in this case only use is made of thedecolorizing capacity, but not of the capacity for binding inorganiccations.

Example 4 A beet sugar molasses of 12 Brix, having a color index of 10Stammer, from which the inorganic cations were removed by ion-exchange,is filtered through cation exchanger K on the one hand and cationexchanger K onthe other hand, which cation exchangers were regeneratedby means of 10% aqueous sulfuric acid (flow rate 5 litres of molassesper one hour and per one litre of exchanger). The degree of decolorizingobtained is disclosed in the following table. The values given thereinLitres of filtrate per litre of exchanger 10 20 30 40 50 60 70 10 0 0 00 O 0 0 0 7O 68 65 65 65 65 64 64 63 O 0 0 0 0 0 0 0 0 40 40 38 38 37 3533 31 30 From these experiments it becomes evident that not only thespongy cation exchangers of the sulfonic acid type, but also thosecontaining car-boxylic acid groups have a considerably higherdecolorizing action than the cation exchangers with homogeneous gelstructure. The high decoiorizing action of the spongy cation exchangersis not only achieved in single filters, but also when these exchangersare used in mixed-bed filters, especially when the mixed-bed filtercontains a spongy cation exchanger and a spongy anion exchwger, and afilter with a cation exchanger in the hydrogen form is applied beforethe mixed-bed filter.

Example 6 Litres of filtrate per litre of exchanger" 5 I 10 I 15 2O 2530 35 M31 99 98 97 96 96 96 75 M132 93 77 (i0 50 30 1O 5 The use of thespongy exchangers in the mixed-bed is of special advantage for thedecolorizing of a dernineralized sugar solution. It is, for instance,possible to pass the sugar solution first through a mixed-bed containingcation and ion exchangers with a homogeneous gel structure and theeafterthrough a mixed-bed with spongy cation and anion exchangers.

The spongy cation exchangers as they may be used for practicing thepresent invention are water-insoluble resins containing sulfonic' acid.and/or carboxylic acid groups bonded to a cross-linked copo'lyrnermatrix of heterogeneous structure, said matrix being obtained bycopolymerizing a monoethylenically monomer such as a monovinyl greasesbenzene, an ot-e-ethylenically unsaturated carboxylic acid or an esterthereof, and a polyethylenically unsaturated monomer, a so-calledcross-linking agent, such as a monomeric polyvinyl benzene, a glycoldi-acrylate or -methacrylate, while dissolved in an inert organicliquid, such as an aliphatic hydrocarbon, which is a non-solvent for thelinear, not cross-linl ed polymers of said monoethylenically unsaturatedmonomers such as polystyrene or polymethacrylate, to produce across-linked copolyrner having occluded therein substantially the totalinert liquid present in the reaction medium and removing said occludedliquid from said copolyrner, the cited inert organic liquid beingpreferably applied in amounts of 30 to 300% by weight as calculated onthe weight of the total monomers, it being furthermore possible to carrythrough said copolymerization in aqueous dispersion. Instead of sulfonicacid or carboxylic acid groups, the resins may also contain phosphonicor phosphinic acid groups as cation exchanging groups. For nearerdetails regarding the production of these resins, reference is made toFrench patent specification 1,205,505 and corresponding applications inother countries, such as United States application Serial No. 727,645,filed April 8, 1958.

As illustrated in the examples, the regeneration of the exhausted spongycation exchangers which have been used for decolor ling sugar solutionsis preferably effected by first applying an aqueous lsolution of aneutral inorganic salt (NaCl, KCl, Na sQ and/ or of a base (NaOl-l, KOH,LiOH, NHQH) and thereafter an aqueous l10% acid solution (HCl, H 50 Incase that the spongy cation exchangers are applied in combination withanion exchangers, both exchangers being arranged in separate filters, itis preferred to use the alkaline regenerant of the anion exchange filterfor the first regeneration step.

The spongy anion exchangers as they are used for practicing the presentinvention may have the same matrix as the spongy cation exchangers,preferably a spongy copolymer of a monovinylbenzene and 240% by weightof a polyvinylbenzene, to Which matrix are bonded by Way of allzylenegroups (such as methylene groups), amine groups or quaternary ammoniumgroups, preferably tertiary amine groups, such as disclosed in the abovecited specifications.

The present invention may be applied to the purification of any sugarsolutions, including cane or beet sugar juices, such as raw sugarsolutions or solutions that occur at any steps of said solutions, rawsugar juices that have been clarified by treatment with lime with orwithout carbonation etc., afiination syrups, mother liquors obtainedfrom massecuites, molasses, glucose solutions, such as corn syrups,maltose syrups, fruit juices, etc.

What is claimed is:

-l. A process for decolorizing a sugar solution which comprises treatingsaid solution with a spongy cationexchange resin and then treating theresulting solution with a spon y anion-exchange resin, each of saidexchange resins being a synthetic non-proliferous Water-insoluble resinhaving as its matrix a cross-linked organic copolymer of heterogeneousstructure, said resins being further characterized in that said spongycation-exchange resin is in the hydrogen form and the matrix is a resinof 90 parts by weight of styrene and about 10 parts by weight of divinylbenzene copolymerized in an inert organic liquid, and said spongyanion-exchange resin is in the hydroxyl form, said anion-exchange resinhaving a plurality of tertiary amino groups and a matr'x prepared fromabout 90 parts by weight of vinyl toluene and about 16 parts by Weightof ethylene glycol dimethacrylate copolyrnerized in aqueous suspensionin an inert organic liquid.

2. The process of decolorizing a sugar solution which comprises treatingsaid sugar solution with a spongy cation-exchange resin in the hydrogenform and having as its matrix a resin prepared by copolymerizing about90 parts of styrene and 10 parts of divinyl benzene in an inert organicliquid, and then contacting the solution with S a Weakly basic spongyanion-exchange resin, the matrix of which is prepared from about partsby weight of styrene and about 10 parts by weight of white spirit, thenamino-methylated, and thereafter alkylated.

3. A process for decolorizing a sugar solution which comprises treatingsaid sugar solution with a spongy cation-exchange resin selected fromthe group consisting of K K and K as defined hereinafter, and thentreating of the resulting solution with a spongy anionexchange resinselected from the group consisting of A and A; as defined hereinafter,wherein K is a spongy cation-exchange resin copolymer of about 90 partsby weight of styrene and 10 parts by weight of divinyl benzenecopolyrnerized in aqueous suspension in the presence of white spirit; Kis a spongy cation-exchange resin c0- polymer containing about 90 partsby Weight of styrene and about 10 parts by weight or" divinyl benzenecopolymerized in normal heptane; K is a spongy carboxyliccation-exchange resin prepared by copolyrnerizing methyl acrylate andabout 5% by weight of divinyl benzene in normal octane; A is a spongyanion-exchange resin copolymer of about 90 parts by Weight of vinyltoluene and about 10 parts by weight of ethylene glycol dimethacrylatecopolyrnerized in normal decanol and thereafter chlorornethylated andaminated; and A is a Weakly basic spongy anion-exchange resin copolyrnerof about 90 parts by weight of styrene and about 10 parts by weight ofdivinyl benzene copolymerized in white spirit, aminomethylated, andthereafter alkylated.

4. The process of claim 3 wherein said cation exchange resin afterexhaustion is regenerated by first treating it with a regenerantselected from the group consisting of an aqueous alkali hydroxidesolution and an alkali metal salt solution and thereafter with anaqueous solution of a mineral acid.

5. The process of claim 3 wherein said sugar solution has inorganicbases removed therefrom before it is contacted with said spongycation-exchange resin.

6. The process of claim 3 wherein said anion-exchange resin afterexhaustion is regenerated by means of an aqueous alkali metal hydroxidesolution, after which said solution is used for regeneration of saidspongy cationexchange resin after its exhaustion.

7. A process for decolorizing a sugar solution which comprises passingsaid sugar solution through a cationexchange resin having a homogeneousgel structure, followed by passing said solution through a spongycationexchange resin selected from the group consisting of K K and K asdefined hereinafter, and then treating the resulting solution with aspongy anion-exchange resin selected from the group consisting of A andA; as defined hereinafter, wherein K2 is a spongy cation-exchange resincopolymer of about 90 parts by weight of styrene and 10 parts by Weightof divinyl benzene copolyrnerized in white spirit; K is a spongycation-exchange resin copolymer containing about 90 parts by weight ofstyrene and about 10 parts by weight of divinyl benzene copolyrnerizedin normal heptane; K is a spongy carboxylic cation-exchange resinprepared by copolymerizing methyl acrylate and about 5% by Weight ofdivinyl benzene in normal octane; A is a spongy anion-exchange resincopolymer of about 90 parts by weight of vinyl toluene and about 10parts by weight of ethylene glycol dimethacrylate copolyrnerized innormal decanol and thereafter chloromethylated and aminated; and A is aWeakly basic spongy anion-exchange resin copolyrner of about 90 parts byweight of styrene and about 10 parts by Weightof a divinyl benzenecopolymerized in White spirit, aminomethylated, and thereafteralleylated.

8. The process of claim 7 wherein said anion-exchange resin is onehaving neutralized quaternary ammonium groups.

9. A process for removing color bodies from a sugar so ution whichcomprises treating said solution both with a cation-exchange resin inthe hydrogen form and with an anion-exchange resin, both resins havingas their matrix a cross-linked copolymer of a monoethylenicallyunsaturated monomer and a polyethylenically unsaturated monomer, saidresin matrix having a spongy structure as the result of conducting thecopolymerization of said monomers while they are dissolved in an inertaliphatic hydrocarbon which is a non-solvent for the polymers of saidmonoethylenically unsaturated mono mers to produce a cross-linkedcopolymer having oceluded therein substmtially the total inert aliphatichydrocarbon, followed by the removal of said occluded hydrocarbon fromthe crosslinked copolymer.

10. The process of claim 9 wherein said cation-exchange resin containsas cation-exchanging groups a member selected from the group consistingof sulfonic acid groups and carboxyl groups.

11. The process of claim 9 wherein said cation-exchange resin afterexhaustion is regenerated with a regenerant selected from the groupconsisting of an aqueous alkali metal hydroxide solution and an alkalimetal salt solution and thereafter with an aqueous solution of a mineralacid.

12. The process of claim 9 wherein said sugar solution has inorganicbases removed therefrom before it is contacted with said spongycation-exchange resin.

13. The process of claim 9 wherein said sugar solution is first treatedwith said spongy cation-exchange resin in the hydrogen form and thenwith said anion-exchange resin in the hydroxide form, saidanion-exchange resin containing tertiary amino groups asanion-exchanging groups.

14. The process of claim 9 wherein said anion-exchange resin afterexhaustion is regenerated by means of an aqueous alkali metal hydroxidesolution, after which said solution is used for regeneration ofsaidspongy cation-exchange resin after exhaustion.

15. A process for removing color bodies from a sugar solution whichcomprises treating said solution with both a granular cation-exchangeresin in the hydrogen form and with an anion-exchange resin, both resinshaving as their matrix a cross-linked copolymer of a monoethylenicallyunsaturated monomer and a polyethylenically unsaturated monomer, saidmatrix having a spongy structure as the result of conducting thecopolymerization of said monomers in aqueous suspension while dissolvedin an inert aliphatic hydrocarbon which is a non-solvent for thepolymers of said monoethylenically unsaturated monomers to producecross-linked copolymers beads having heterogeneously occluded thereinsubstantially all of said inert aliphatic hydrocarbon, followed byremoval of said occluded hydrocarbon from the beads.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Chem Abstracts, vol. 52, page 17767 f. Nachod et al.: IonExchange Technology, 1956, demic Press Inc., N.Y., pages 544-545 and11-12.

Aca-

1. A PROCESS FOR DECOLORIZING A SUGAR SOLUTION WHICH COMPRISES TREATINGSAID SOLUTION WITH A SPONGY CATIONEXCHANGE RESIN AND THEN TREATING THERESULTING SOLUTION WITH A SPONGY ANION-EXCHANGE RESIN, EACH OF SAIDEXCHANGE RESIN BEING A SYNTHETIC NON-PROLIFEROUS WATER-INSOLUBLE RESINHAVING AS ITS MATRIX A CROSS-LINKED ORGANIC COPOLYMER OF HETEROGENEOUSSTRUCTURE, SAID RESINS BEING FURTHER CHARACTERIZED IN THAT SAID SPONGYCATION-EXCHANGE RESIN IS IN THE HYDROGEN FORM AND THE MATRIX IS A RESINOF 90 PARTS BY WEIGHT OF STRYRENE AND ABOUT 10 PARTS BY WEIGHT OFDIVINYL BENZENE COPOLYMERIZED IN AN INERT ORGANIC LIQUID, AND SAIDSPONGY ANION-EXCHANGE RESIN IS IN THE HYDROXYL FORM, SAID ANION-EXCHANGERESIN HAVING A PLURALITY OF TERTIARY AMINO GROUPS AND A MATRIX PREPAREDFROM ABOUT 90 PARTS BY WEIGHT OF VINYL TOLUENE AND ABOUT 10 PARTS BYWEIGHT OF ETHYLENE GLYCOL DIMETHACRYLTE COPOLYMERIZED IN AQUEOUSSUSPENSION IN AN INERT ORGANIC LIQUID.